github_workflows_autoset-markdownpage-date.yml

name: Auto-set markdownpages frontmatter date

on:
  pull_request:
    types: [opened, synchronize, reopened]
    paths:
      - 'markdownpages/**'

permissions:
  contents: write
  pull-requests: write

jobs:
  set-date:
    if: github.event.pull_request.head.repo.full_name == github.repository
    runs-on: ubuntu-latest

    steps:
      - name: Checkout PR branch
        uses: actions/checkout@v4
        with:
          ref: ${{ github.event.pull_request.head.ref }}
          fetch-depth: 0

      - name: Update frontmatter date to today
        shell: bash
        run: |
          set -euo pipefail

          BASE="${{ github.event.pull_request.base.sha }}"
          HEAD="${{ github.event.pull_request.head.sha }}"
          TODAY="$(date -u +%Y-%m-%d)"   # Change to local TZ if needed

          echo "Using date: $TODAY"

          if ! CHANGED_FILES=$(git diff --name-only "$BASE" "$HEAD" -- 'markdownpages/**/*.md' 'markdownpages/*.md'); then
            echo "::error::Failed to determine changed markdownpages files between $BASE and $HEAD"
            exit 1
          fi
          if [[ -z "$CHANGED_FILES" ]]; then
            echo "No changed markdownpages files."
            exit 0
          fi

          changed_any=0

          while IFS= read -r file; do
            [[ -f "$file" ]] || continue

            # Ensure file starts with frontmatter
            if ! head -n1 "$file" | grep -qx '---'; then
              echo "Skipping $file (no frontmatter at top)"
              continue
            fi

            # If date exists in frontmatter, replace first occurrence.
            # Otherwise insert date line right before closing frontmatter.
            if awk '
              NR==1 && $0=="---" {infm=1; next}
              infm && $0=="---" {exit}
              infm && $0 ~ /^date:[[:space:]]*/ {found=1}
              END {exit(found?0:1)}
            ' "$file"; then
              awk -v today="$TODAY" '
                BEGIN {infm=0; done=0}
                NR==1 && $0=="---" {infm=1; print; next}
                infm && $0=="---" {
                  infm=0
                  print
                  next
                }
                infm && !done && $0 ~ /^date:[[:space:]]*/ {
                  print "date: " today
                  done=1
                  next
                }
                {print}
              ' "$file" > "$file.tmp" && mv "$file.tmp" "$file"
              echo "Updated date in $file"
              changed_any=1
            else
              awk -v today="$TODAY" '
                BEGIN {infm=0; inserted=0}
                NR==1 && $0=="---" {infm=1; print; next}
                infm && $0=="---" && !inserted {
                  print "date: " today
                  inserted=1
                  print
                  infm=0
                  next
                }
                {print}
              ' "$file" > "$file.tmp" && mv "$file.tmp" "$file"
              echo "Inserted date in $file"
              changed_any=1
            fi
          done <<< "$CHANGED_FILES"

          if [[ "$changed_any" -eq 0 ]]; then
            echo "No files changed by updater."
            exit 0
          fi

      - name: Commit and push if changed
        shell: bash
        run: |
          set -euo pipefail
          if git diff --quiet; then
            echo "No git changes to commit."
            exit 0
          fi

          git config user.name "github-actions[bot]"
          git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
          git add markdownpages
          git commit -m "chore: auto-update markdownpages frontmatter date to today"
          git push